1. Field of the Invention
The present invention relates to an image forming apparatus and a cartridge detachably mountable to such an image forming apparatus and more particularly, it relates to an image forming apparatus capable of detecting a remaining amount of developer and a cartridge detachably mountable to such an image forming apparatus.
Here, an electrophotographic image forming apparatus as an example of the image forming apparatus may be, for example, an electrophotographic copying machine, an electrophotographic printer (for example, LED printer, laser beam printer or the like), an electrophotographic facsimile or the like.
Further, a process cartridge detachably mountable to a main body (assembly) of the image forming apparatus may incorporate therein at least one of an electrophotographic photosensitive member, charging means for charging the electrophotographic photosensitive member, developing means for supplying developer to the electrophotographic photosensitive member and cleaning means for cleaning the electrophotographic photosensitive member. In particular, the process cartridge may incorporate therein at least one of charging means, developing means and cleaning means, and an electrophotographic photosensitive member as a cartridge unit which can be detachably mounted to a main body of the image forming apparatus or may incorporate therein at least an electrophotographic photosensitive member and developing means as a cartridge unit which can be detachably mounted to a main body of the image forming apparatus.
2. Related Background Art
In conventional electrophotographic image forming apparatuses of the electrophotographic type, such as an electrophotographic copying machine, a laser beam printer or the like, a latent image is formed on an electrophotographic photosensitive member by illuminating the photosensitive member with a beam corresponding to image information, and developer (including toner) is supplied to the latent image by using developing means to visualize the latent image as a toner image, which is, in turn, transferred from the photosensitive member onto a recording medium, thereby forming an image on the recording medium. A developer containing container is connected to the developing means so that the developer is consumed by image formation.
In such an image forming apparatus, in order to facilitate exchange and maintenance of consumption parts, such as the electrophotographic photosensitive member and the developer, the electrophotographic photosensitive member and the developing means, charging means and cleaning means as process means acting on the electrophotographic photosensitive member and further a developer containing container and a waste developer container are integrally incorporated as a process cartridge that can be detachably mounted to a main body of the image forming apparatus. According to the process-cartridge system, since maintenance of the apparatus can be performed by the user himself without any expert, operability can be improved considerably. Thus, the process cartridge system has widely been used in the electrophotographic image forming apparatus.
Further, for example, in a color image forming apparatus having a plurality of color developing means, when the consumption degrees of the respective developing means are different, respective color developing cartridges may be formed by integrally incorporating the respective color developing means and corresponding developer containing containers, and such cartridges can detachably be mounted to the image forming apparatus to permit exchange independently.
In such image forming apparatuses of the cartridge type, the user permits the image formation again by exchanging the cartridge when the developer is used up. To this end, in some cases, such an image forming apparatus is provided with means for detecting the fact that the developer is used up and for informing the user of such fact, i.e., a developer amount detecting device.
Regarding the developer amount detecting device, in order to always know the amount of developer to be supplied for image formation remaining within the cartridge, developer remaining amount detecting means capable of detecting the developer remaining amount level are provided on the cartridge or the main body of the image forming apparatus.
Particularly, there is a technique in which the user""s convenience is further enhanced not only by informing the user of the fact that the developer is used up but also by successively detecting and informing the user of the amount of the developer. In an image forming apparatus incorporating such a technique, the percentage (with respect to the unused condition) of the developer remaining amount may be calculated and a calculated result be successively communicated to the user, or the xe2x80x9cabsence of developerxe2x80x9d indicating the fact that the developer is decreased to the extent that image formation cannot be effected with a predetermined quality may be determined, thereby warning the user of the fact that the remaining developer is insufficient, before a poor image is generated.
As an example of such developer remaining amount detecting means, there is a plate antenna system. According to this plate antenna system, for example, metal plates constituting electrodes are installed at locations opposed to a developer bearing member of the developing means or at other plural locations, and the fact that capacitances between the metal plates and the developer bearing member and between the metal plates are varied with the amount of developer such as insulation toner is utilized.
That is to say, if gaps between the metal plates and the developer bearing member and between the metal plates are filled with the developer, the capacitances therebetween become greater, and, as the developer is decreased, the air occupying ratio in the gaps is increased, with the result that the capacitances are decreased. Accordingly, by previously seeking a relationship between the capacitances (between the metal plates and the developer bearing member and between the metal plates) and the developer amount, the developer amount level can be detected by measuring the capacitances.
The measurement of the capacitance is effected by measuring electric current flowing to the metal plate from the developer bearing member when AC bias is applied to the developer bearing member. Alternatively, when a plurality of metal plates are provided, by measuring electric current flowing from one of the metal plates to the other metal plate when AC bias is applied to one of the metal plates as electrodes, the capacitance between the metal plates can be measured similarly. In the developer amount detecting device of the plate antenna type, in many cases, during the image formation in which the developing bias is applied to the developer bearing member, the developer amount is detected.
However, as mentioned above, even when the developer remaining amount detecting means capable of detecting the developer remaining amount level is provided, in some cases, the value of the developer remaining amount detected by the developer remaining amount detecting means does not coincide with the amount of the developer actually remaining in the developing device. In this case, the developer remaining amount cannot be detected correctly.
For example, in case of the above-mentioned developer amount detecting device of the plate antenna type, the capacitances between the developer bearing member and the metal plates as electrodes or the capacitances between the metal plates depend upon respective positional relationships. That is to say, even when there is no developer in the developing device, if a distance between both (developer bearing member and metal plate or metal plate and metal plate) is small, the absolute value of the capacitance becomes greater, whereas, if the distance between both is great, the absolute value of the capacitance becomes smaller. Thus, for example, due to tolerance of the metal plates of the developer remaining amount detecting means, there may be dispersion in the developer amount detecting value from cartridge to cartridge. Further, due to differences in the manufacturing lots of developer contained in the developing device, the using environment and tolerance of parts of the cartridge and the electronic parts of the main body of the image forming apparatus, dispersion in developer amount detecting value may occur.
Accordingly, when the developer remaining amount level is detected by using the previously set relationship between the detection value of the capacitance and the developer amount, the detected result may be different from the amount of the developer actually remaining in the developing device.
Namely, when the developing device is filled with the developer (developer full condition), i.e., in the initial use of the process cartridge, in case of a process cartridge in which the capacitance detection value obtained by the developer remaining amount detecting means is greater than the set value (ideal value), since the developer amount detecting device always detects a value greater than the actual developer remaining amount during the usage of the process cartridge, the amount of the developer becomes smaller than the predetermined value before the user is informed of the xe2x80x9cabsence of developerxe2x80x9d, thereby generating a so-called blank stripe image.
To the contrary, in case of a process cartridge in which the capacitance detection value in the developer full condition is smaller than the set value, since the developer amount detecting device always detects a value smaller than the actual developer remaining amount during the usage of the process cartridge, in spite of the fact that there is much developer in the developing device, the user may be warned of the xe2x80x9cabsence of developerxe2x80x9d. And, if the user exchanges the process cartridge for a new one in accordance with such alarming, a large amount of toner will be unused, thereby wasting resources too much. The present invention aims to eliminate such a problem.
The present invention aims to eliminate the above-mentioned problems, and an object of the present invention is to provide an image forming apparatus and a process cartridge detach ably mountable to such an image forming apparatus, in which a remaining amount of developer can be detected correctly.
Another object of the present invention is to provide an image forming apparatus and a process cartridge detachably mountable to such an image forming apparatus, in which a remaining amount of developer can be detected correctly even if there is an individual difference in an image forming apparatus or an individual unit mounted to such an image forming apparatus (particularly, remaining amount detecting means therein.
A further object of the present invention is to provide an image forming apparatus comprising a developer container for containing developer, the container being detachably mountable to a main assembly of the image forming apparatus, developer amount detecting means for detecting an amount of the developer contained in the developer container, and determining means for determining the amount of the developer in accordance with a maximum value of a detection amount of the developer amount detecting means.
A still further object of the present invention is to provide an image forming apparatus comprising a developer container for containing developer, developer amount detecting means for detecting an amount of the developer contained in the developer container, a memory, and recording means for recording a detection amount of the developer amount detecting means in the memory, the recording means renewing the detection amount stored in the memory whenever the detection amount of the detecting means becomes greater than the detection value stored in the memory.
A further object of the present invention is to provide a unit comprising a memory, and a developer container for containing a developer, and wherein the memory stores a maximum value of a detection amount of developer amount detecting means for detecting an amount of the developer contained in the developer container.
A still further object of the present invention is to provide an image forming apparatus comprising a developer container for containing a developer, the container being detachably mountable to a main assembly of the image forming apparatus, developer amount detecting means for detecting an amount of the developer contained in the developer container, and determining means for determining the amount of the developer in accordance with an average value of plural detection amounts of the detecting means.
A further object of the present invention is to provide a unit comprising a memory, and a developer container for containing a developer, and wherein the memory stores plural detection amounts of the developer amount detecting means for detecting the amount of the developer contained in the developer container.
A still further object of the present invention is to provide an image forming apparatus comprising a developer container for containing a developer, the container being detachably mountable to a main assembly of the image forming apparatus, developer amount detecting means for detecting an amount of the developer contained in the developer container, and determining means for determining the amount of the developer in accordance with a detection amount of the developer amount detecting means when the developer is not filled in the container.
A further object of the present invention is to provide a unit comprising a memory, and a developer container for containing developer, and wherein the memory stores a detection amount of the developer amount detecting means when the developer is not filled in the container.
A still further object of the present invention is to provide an image forming apparatus comprising a developer container detachably mountable to a main assembly of the image forming apparatus, the container having a first room and a second room, developer amount detecting means which is arranged in the first room for detecting the amount of developer, a seal member for sealing the developer in the second room, and determining means for determining the amount of the developer in accordance with a detection amount of the detecting means before the seal member is removed.
A further object of the present invention is to provide a unit comprising a memory, and a developer container for containing a developer, the container having a first room and a second room, developer amount detecting means which is arranged in the first room for detecting the amount of the developer, and a seal member for sealing the developer in the second room, wherein the memory stores a detection amount of the detecting means before the seal member is removed.
These and other objects of the present invention will become more apparent upon consideration of the following description of the preferred embodiments of the present invention taken in conjunction with the accompanying drawings.
FIG. 1 is a sectional view showing an embodiment of a process cartridge and an image forming apparatus according to the present invention;
FIG. 2 is an enlarged sectional view of the process cartridge of FIG. 1;
FIG. 3 is a schematic view showing the relationship between a memory of the process cartridge according to the first embodiment and a control portion of a main body of the image forming apparatus;
FIG. 4 is a graph showing a relationship between the detected voltage value of a developer amount detecting device constructed in accordance with the present invention and a developer remaining amount;
FIG. 5 is a flow chart for explaining a developer amount detecting operation using memory means of the cartridge according to the first embodiment;
FIG. 6 is a graph for explaining the indication of a developer remaining amount after the detected voltage value of the developer amount detecting device is corrected in the first embodiment;
FIG. 7 is a sectional view of a developing device constructed as a cartridge according to a second embodiment of the present invention;
FIG. 8 is a sectional view showing a process cartridge and an image forming apparatus according to third to seventh embodiments of the present invention;
FIG. 9 is an enlarged sectional view of the process cartridge of FIG. 8;
FIG. 10 is a view showing an example of a circuit arrangement for detecting the developer amount in the process cartridge in the third to eighth embodiments;
FIG. 11 is a schematic view showing the relationship between a memory of the process cartridge according to the third embodiment and a control portion of a main body of the image forming apparatus;
FIG. 12 is a graph showing the relationship between a detected voltage value of a developer amount detecting device and a developer remaining amount;
FIG. 13 is a graph showing the relationship between a detected voltage value of a developer amount detecting device constructed in accordance with the present invention and the developer remaining amount;
FIG. 14 is a flow chart for explaining a developer amount detecting operation using a developer correction table and memory means of the cartridge according to the third embodiment;
FIGS. 15A, 15B and 15C are graphs for explaining an effect of the developer amount detecting operation according to the present invention;
FIG. 16 is a flow chart for explaining a developer amount detecting operation using a developer correction table and memory means of the cartridge according to the fourth embodiment;
FIG. 17 is a flow chart for explaining a developer amount detecting operation using a developer correction table and memory means of the cartridge according to the fifth embodiment;
FIG. 18 is a flow chart for explaining a developer amount detecting operation using a developer correction table and memory means of the cartridge according to the sixth embodiment;
FIG. 19 is a flow chart for explaining a developer amount detecting operation using a developer correction table and memory means of the cartridge according to the seventh embodiment;
FIG. 20 is a sectional view of a developing device as a cartridge according to the eighth embodiment;
FIG. 21 is a schematic view showing the relationship between a cartridge according to a ninth embodiment of the present invention and a main body of an image forming apparatus, for explaining a control arrangement of a memory of the cartridge;
FIG. 22 is a graph showing the relationship between the detected voltage value of the developer amount detecting device constructed in accordance with the present invention and the developer remaining amount;
FIG. 23 is a flow chart for explaining the developer amount detecting operation using memory means of the cartridge according to the ninth embodiment;
FIG. 24 is a graph for explaining the display of the developer remaining amount after the detected voltage value of the developer amount detecting device is corrected in accordance with the ninth embodiment;
FIG. 25 is a schematic view showing the relationship between a cartridge according to a tenth embodiment of the present invention and a main body of an image forming apparatus, for explaining a control arrangement of a memory of the cartridge;
FIG. 26 is a flow chart for explaining the developer amount detecting operation using memory means of the cartridge according to the tenth embodiment;
FIG. 27 is a graph for explaining the display of the developer remaining amount after the detected voltage value of the developer amount detecting device is corrected in accordance with the tenth embodiment;
FIG. 28 is a sectional view of a developing device as a cartridge according to an eleventh embodiment of the present invention;
FIG. 29 is a sectional view of a process cartridge according to a twelfth embodiment of the present invention and an image forming apparatus;
FIG. 30 is an enlarged sectional view of the process cartridge of FIG. 29;
FIG. 31 is a view showing a circuit arrangement of a developer amount detecting device used in the twelfth embodiment of the present invention;
FIG. 32 is a schematic view showing the relationship between a process cartridge according to the twelfth embodiment and a main body of the image forming apparatus, for explaining a control arrangement of a memory of the cartridge;
FIG. 33 is a graph showing the relationship between a detected voltage value of the developer amount detecting device constructed in accordance with the present invention and a developer remaining amount;
FIG. 34 is a longitudinal sectional view of a developer seal member;
FIG. 35 is a flow chart showing a PAE value storing operation according to the twelfth embodiment;
FIG. 36 is a flow chart for explaining a developer amount detecting operation using memory means of the cartridge according to the twelfth embodiment;
FIG. 37 is a graph for explaining the display of the developer remaining amount after the detected voltage value of the developer amount detecting device is corrected in accordance with the twelfth embodiment;
FIG. 38 is a schematic view showing the relationship between a process cartridge according to a thirteenth embodiment of the present invention and a main body of an image forming apparatus, for explaining a control arrangement of a memory of the cartridge;
FIGS. 39 to 41 are a flow chart for explaining a developer amount detecting operation using memory means of the cartridge according to the thirteenth embodiment;
FIG. 42 is a graph for explaining the display of a developer remaining amount after a detected voltage value of a developer amount detecting device is corrected in accordance with the thirteenth embodiment;
FIG. 43 is a schematic view showing the relationship between a memory of a process cartridge according to a fifteenth embodiment of the present invention and a control portion of a main body of an image forming apparatus;
FIG. 44 is a graph showing the relationship between a detected voltage value of a developer amount detecting device constructed in accordance with the present invention and a developer remaining amount;
FIGS. 45 and 46 are a flow chart for explaining a developer amount detecting operation using memory means of the cartridge according to the fifteenth embodiment;
FIG. 47 is a graph showing the relationship between the display of the developer remaining amount and the detected voltage value after correction in accordance with fifteenth embodiment;
FIG. 48 is a schematic view showing the relationship between a memory of a process cartridge according to a sixteenth embodiment of the present invention and a control portion of a main body of an image forming apparatus;
FIGS. 49 and 50 are a flow chart for explaining a developer amount detecting operation using memory means of the cartridge according to the sixteenth embodiment;
FIG. 51 is a graph showing the relationship between the display of a developer remaining amount and the detected voltage value after correcting in accordance with sixteenth embodiment;
FIG. 52 is a sectional view of a process cartridge according to a seventeenth embodiment of the present invention;
FIG. 53 is a graph showing a relationship between the detected voltage value of a conventional developer amount detecting device and a developer remaining amount;
FIG. 54 is a graph showing the relationship between the detected voltage value of the developer amount detecting device according to the seventeenth embodiment and the developer remaining amount;
FIGS. 55 and 56 are a flow chart for explaining a developer amount detecting operation using memory means of the cartridge according to the seventeenth embodiment;
FIG. 57 is a graph showing a relationship between the detected voltage value of a developer amount detecting device according to an eighteenth embodiment of the present invention and a developer remaining amount; and
FIG. 58 is a flow chart for explaining a control sequence until threshold voltage is sought.